21 research outputs found
Experimental Observation of Environment-induced Sudden Death of Entanglement
We demonstrate the difference between local, single-particle dynamics and
global dynamics of entangled quantum systems coupled to independent
environments. Using an all-optical experimental setup, we show that, while the
environment-induced decay of each system is asymptotic, quantum entanglement
may suddenly disappear. This "sudden death" constitutes yet another distinct
and counter-intuitive trait of entanglement.Comment: 4 pages, 4 figure
Emergence of the pointer basis through the dynamics of correlations
We use the classical correlation between a quantum system being measured and
its measurement apparatus to analyze the amount of information being retrieved
in a quantum measurement process. Accounting for decoherence of the apparatus,
we show that these correlations may have a sudden transition from a decay
regime to a constant level. This transition characterizes a non-asymptotic
emergence of the pointer basis, while the system-apparatus can still be quantum
correlated. We provide a formalization of the concept of emergence of a pointer
basis in an apparatus subject to decoherence. This contrast of the pointer
basis emergence to the quantum to classical transition is demonstrated in an
experiment with polarization entangled photon pairs.Comment: 4+2 pgs, 3 figures. Title changed. Revised version to appear on PR
Experimental investigation of the dynamics of entanglement: Sudden death, complementarity, and continuous monitoring of the environment
We report on an experimental investigation of the dynamics of entanglement
between a single qubit and its environment, as well as for pairs of qubits
interacting independently with individual environments, using photons obtained
from parametric down-conversion. The qubits are encoded in the polarizations of
single photons, while the interaction with the environment is implemented by
coupling the polarization of each photon with its momentum. A convenient Sagnac
interferometer allows for the implementation of several decoherence channels
and for the continuous monitoring of the environment. For an
initially-entangled photon pair, one observes the vanishing of entanglement
before coherence disappears. For a single qubit interacting with an
environment, the dynamics of complementarity relations connecting single-qubit
properties and its entanglement with the environment is experimentally
determined. The evolution of a single qubit under continuous monitoring of the
environment is investigated, demonstrating that a qubit may decay even when the
environment is found in the unexcited state. This implies that entanglement can
be increased by local continuous monitoring, which is equivalent to
entanglement distillation. We also present a detailed analysis of the transfer
of entanglement from the two-qubit system to the two corresponding
environments, between which entanglement may suddenly appear, and show
instances for which no entanglement is created between dephasing environments,
nor between each of them and the corresponding qubit: the initial two-qubit
entanglement gets transformed into legitimate multiqubit entanglement of the
Greenberger-Horne-Zeilinger (GHZ) type.Comment: 15 pages, 14 figures; only .ps was working, now .pdf is also
availabl
Observation of the entanglement sudden death
We demonstrate, using an all-optical setup, the difference between local and global dynamics of entangled quantum systems coupled to independent environments. Even when the decay of each system is asymptotic, quantum entanglement may suddenly disappear. We also demonstrate experimentally that measurements performed in the environment affects the local evolution. (C) 2007 Optical Society of America OCIS codes: (270.0270) Genera
Environment-induced sudden death of entanglement
We demonstrate the difference between local, single-particle dynamics and global dynamics of entangled quantum systems coupled to independent environments. Using an all-optical experimental setup, we showed that, even when the environment-induced decay of each system is asymptotic, quantum entanglement may suddenly disappear. This "sudden death" constitutes yet another distinct and counterintuitive trait of entanglement